diff options
Diffstat (limited to 'toys/pending/telnet.c')
| -rw-r--r-- | toys/pending/telnet.c | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/toys/pending/telnet.c b/toys/pending/telnet.c new file mode 100644 index 00000000..e0f9f6f0 --- /dev/null +++ b/toys/pending/telnet.c @@ -0,0 +1,386 @@ +/* telnet.c - Telnet client. + * + * Copyright 2012 Madhur Verma <mad.flexi@gmail.com> + * Copyright 2013 Kyungwan Han <asura321@gmail.com> + * Modified by Ashwini Kumar <ak.ashwini1981@gmail.com> + * + * Not in SUSv4. + +USE_TELNET(NEWTOY(telnet, "<1>2", TOYFLAG_BIN)) + +config TELNET + bool "telnet" + default n + help + usage: telnet HOST [PORT] + Connect to telnet server +*/ + +#define FOR_telnet +#include "toys.h" +#include <arpa/telnet.h> +#include <netinet/in.h> +#include <sys/poll.h> + +GLOBALS( + int port; + int sfd; + char buff[128]; + int pbuff; + char iac[256]; + int piac; + char *ttype; + struct termios def_term; + struct termios raw_term; + uint8_t term_ok; + uint8_t term_mode; + uint8_t flags; + unsigned win_width; + unsigned win_height; + unsigned signalno; +) + +#define DATABUFSIZE 128 +#define IACBUFSIZE 256 +#define CM_TRY 0 +#define CM_ON 1 +#define CM_OFF 2 +#define UF_ECHO 0x01 +#define UF_SGA 0x02 + +/* + * creates a socket of family INET/INET6 and protocol TCP and connects + * it to HOST at PORT. + * if successful then returns SOCK othrwise error + */ +static int xconnect_inet_tcp(char *host, int port) +{ + int ret; + struct addrinfo *info, *rp; + char buf[32]; + + rp = xzalloc(sizeof(struct addrinfo)); + rp->ai_family = AF_UNSPEC; + rp->ai_socktype = SOCK_STREAM; + rp->ai_protocol = IPPROTO_TCP; + sprintf(buf, "%d", port); + + ret = getaddrinfo(host, buf, rp, &info); + if(ret || !info) perror_exit("BAD ADDRESS: can't find : %s ", host); + free(rp); + + for (rp = info; rp; rp = rp->ai_next) + if ( (rp->ai_family == AF_INET) || (rp->ai_family == AF_INET6)) break; + + if (!rp) error_exit("Invalid IP %s", host); + + ret = xsocket(rp->ai_family, SOCK_STREAM, IPPROTO_TCP); + if(connect(ret, rp->ai_addr, rp->ai_addrlen) == -1) perror_exit("connect"); + + freeaddrinfo(info); + return ret; +} + +// sets terminal mode: LINE or CHARACTER based om internal stat. +static char const es[] = "\r\nEscape character is "; +static void set_mode(void) +{ + if (TT.flags & UF_ECHO) { + if (TT.term_mode == CM_TRY) { + TT.term_mode = CM_ON; + printf("\r\nEntering character mode%s'^]'.\r\n", es); + if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term); + } + } else { + if (TT.term_mode != CM_OFF) { + TT.term_mode = CM_OFF; + printf("\r\nEntering line mode%s'^C'.\r\n", es); + if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + } + } +} + +// flushes all data in IAC buff to server. +static void flush_iac(void) +{ + int wlen = write(TT.sfd, TT.iac, TT.piac); + + if(wlen <= 0) error_msg("IAC : send failed."); + TT.piac = 0; +} + +// puts DATA in iac buff of length LEN and updates iac buff pointer. +static void put_iac(int len, ...) +{ + va_list va; + + if(TT.piac + len >= IACBUFSIZE) flush_iac(); + va_start(va, len); + for(;len > 0; TT.iac[TT.piac++] = (uint8_t)va_arg(va, int), len--); + va_end(va); +} + +// puts string STR in iac buff and updates iac buff pointer. +static void str_iac(char *str) +{ + int len = strlen(str); + + if(TT.piac + len + 1 >= IACBUFSIZE) flush_iac(); + strcpy(&TT.iac[TT.piac], str); + TT.piac += len+1; +} + +static void handle_esc(void) +{ + char input; + + if(TT.signalno && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term); + write(1,"\r\nConsole escape. Commands are:\r\n\n" + " l go to line mode\r\n" + " c go to character mode\r\n" + " z suspend telnet\r\n" + " e exit telnet\r\n", 114); + + if (read(STDIN_FILENO, &input, 1) <= 0) { + if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + exit(0); + } + + switch (input) { + case 'l': + if (!TT.signalno) { + TT.term_mode = CM_TRY; + TT.flags &= ~(UF_ECHO | UF_SGA); + set_mode(); + put_iac(6, IAC,DONT,TELOPT_ECHO,IAC,DONT, TELOPT_SGA); + flush_iac(); + goto ret; + } + break; + case 'c': + if (TT.signalno) { + TT.term_mode = CM_TRY; + TT.flags |= (UF_ECHO | UF_SGA); + set_mode(); + put_iac(6, IAC,DO,TELOPT_ECHO,IAC,DO,TELOPT_SGA); + flush_iac(); + goto ret; + } + break; + case 'z': + if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + kill(0, SIGTSTP); + if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term); + break; + case 'e': + if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + exit(0); + default: break; + } + + write(1, "continuing...\r\n", 15); + if (TT.signalno && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + +ret: + TT.signalno = 0; +} + +/* + * handles telnet SUB NEGOTIATIONS + * only terminal type is supported. + */ +static void handle_negotiations(void) +{ + char opt = TT.buff[TT.pbuff++]; + + switch(opt) { + case TELOPT_TTYPE: + opt = TT.buff[TT.pbuff++]; + if(opt == TELQUAL_SEND) { + put_iac(4, IAC,SB,TELOPT_TTYPE,TELQUAL_IS); + str_iac(TT.ttype); + put_iac(2, IAC,SE); + } + break; + default: break; + } +} + +/* + * handles server's DO DONT WILL WONT requests. + * supports ECHO, SGA, TTYPE, NAWS + */ +static void handle_ddww(char ddww) +{ + char opt = TT.buff[TT.pbuff++]; + + switch (opt) { + case TELOPT_ECHO: /* ECHO */ + if (ddww == DO) put_iac(3, IAC,WONT,TELOPT_ECHO); + if(ddww == DONT) break; + if (TT.flags & UF_ECHO) { + if (ddww == WILL) return; + } else if (ddww == WONT) return; + if (TT.term_mode != CM_OFF) TT.flags ^= UF_ECHO; + (TT.flags & UF_ECHO)? put_iac(3, IAC,DO,TELOPT_ECHO) : + put_iac(3, IAC,DONT,TELOPT_ECHO); + set_mode(); + printf("\r\n"); + break; + + case TELOPT_SGA: /* Supress GO Ahead */ + if (TT.flags & UF_SGA){ if (ddww == WILL) return; + } else if (ddww == WONT) return; + + TT.flags ^= UF_SGA; + (TT.flags & UF_SGA)? put_iac(3, IAC,DO,TELOPT_SGA) : + put_iac(3, IAC,DONT,TELOPT_SGA); + break; + + case TELOPT_TTYPE: /* Terminal Type */ + (TT.ttype)? put_iac(3, IAC,WILL,TELOPT_TTYPE): + put_iac(3, IAC,WONT,TELOPT_TTYPE); + break; + + case TELOPT_NAWS: /* Window Size */ + put_iac(3, IAC,WILL,TELOPT_NAWS); + put_iac(9, IAC,SB,TELOPT_NAWS,(TT.win_width >> 8) & 0xff, + TT.win_width & 0xff,(TT.win_height >> 8) & 0xff, + TT.win_height & 0xff,IAC,SE); + break; + + default: /* Default behaviour is to say NO */ + if(ddww == WILL) put_iac(3, IAC,DONT,opt); + if(ddww == DO) put_iac(3, IAC,WONT,opt); + break; + } +} + +/* + * parses data which is read from server of length LEN. + * and passes it to console. + */ +static int read_server(int len) +{ + int i = 0; + char curr; + TT.pbuff = 0; + + do { + curr = TT.buff[TT.pbuff++]; + if (curr == IAC) { + curr = TT.buff[TT.pbuff++]; + switch (curr) { + case DO: /* FALLTHROUGH */ + case DONT: /* FALLTHROUGH */ + case WILL: /* FALLTHROUGH */ + case WONT: + handle_ddww(curr); + break; + case SB: + handle_negotiations(); + break; + case SE: + break; + default: break; + } + } else { + toybuf[i++] = curr; + if (curr == '\r') { curr = TT.buff[TT.pbuff++]; + if (curr != '\0') TT.pbuff--; + } + } + } while (TT.pbuff < len); + + if (i) write(STDIN_FILENO, toybuf, i); + return 0; +} + +/* + * parses data which is read from console of length LEN + * and passes it to server. + */ +static void write_server(int len) +{ + char *c = (char*)TT.buff; + int i = 0; + + for (; len > 0; len--, c++) { + if (*c == 0x1d) { + handle_esc(); + return; + } + toybuf[i++] = *c; + if (*c == IAC) toybuf[i++] = *c; /* IAC -> IAC IAC */ + else if (*c == '\r') toybuf[i++] = '\0'; /* CR -> CR NUL */ + } + if(i) write(TT.sfd, toybuf, i); +} + +/* + * SIGINT signal handling. + * only sets signalno which get handle in main loop. + */ +static void handle_sigint(int signo) +{ + TT.signalno = signo; +} + +void telnet_main(void) +{ + int set = 1, len; + struct pollfd pfds[2]; + + TT.port = 23; //TELNET_PORT + TT.win_width = 80; //columns + TT.win_height = 24; //rows + + if(toys.optc == 2) TT.port = atoi(toys.optargs[1]); + if(TT.port <= 0 || TT.port > 65535) + error_exit("PORT can be non-zero upto 65535."); + + TT.ttype = getenv("TERM"); + if(!TT.ttype) TT.ttype = ""; + if(strlen(TT.ttype) > IACBUFSIZE-1) TT.ttype[IACBUFSIZE - 1] = '\0'; + + if (!tcgetattr(0, &TT.def_term)) { + TT.term_ok = 1; + TT.raw_term = TT.def_term; + cfmakeraw(&TT.raw_term); + } + terminal_size(&TT.win_width, &TT.win_height); + + TT.sfd = xconnect_inet_tcp(toys.optargs[0], TT.port); + setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(set)); + setsockopt(TT.sfd, SOL_SOCKET, SO_KEEPALIVE, &set, sizeof(set)); + + pfds[0].fd = STDIN_FILENO; + pfds[0].events = POLLIN; + pfds[1].fd = TT.sfd; + pfds[1].events = POLLIN; + + TT.piac = TT.pbuff = 0; + TT.signalno = 0; + signal(SIGINT, handle_sigint); + while(1) { + if(TT.piac) flush_iac(); + if(poll(pfds, 2, -1) < 0) { + (TT.signalno)?handle_esc():sleep(1); + continue; + } + if(pfds[0].revents) { + len = read(STDIN_FILENO, TT.buff, DATABUFSIZE); + if(len > 0) write_server(len); + else return; + } + if(pfds[1].revents) { + len = read(TT.sfd, TT.buff, DATABUFSIZE); + if(len > 0) read_server(len); + else { + printf("Connection closed by foreign host\r\n"); + if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term); + exit(1); + } + } + } +} |